<!DOCTYPE html>
<html>

<head lang="en">
  <meta charset="UTF-8">
  <title></title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    .nav {
      height: 30px;
      background: #036663;
      border-bottom: 1px solid #369;
      line-height: 30px;
      padding-left: 30px;
    }

    .nav a {
      color: #fff;
      text-align: center;
      font-size: 14px;
      text-decoration: none;

    }

    .d-box {
      width: 400px;
      height: 300px;
      border: 5px solid #eee;
      box-shadow: 2px 2px 2px 2px #666;
      position: absolute;
      top: 40%;
      left: 40%;
      background-color: white;

      /* 不让文字被选中 */
      -webkit-user-select: none;
      -moz-user-select: none;
      -ms-user-select: none;
      user-select: none;
    }

    .hd {
      width: 100%;
      height: 25px;
      background-color: #7c9299;
      border-bottom: 1px solid #369;
      line-height: 25px;
      color: white;
      cursor: move;
    }

    #box_close {
      float: right;
      cursor: pointer;
    }
  </style>
</head>

<body id="bo">
  <div class="nav">
    <a href="javascript:;" id="register">注册信息</a>
  </div>
  <div class="d-box" id="d_box">
    <div class="hd" id="drop">注册信息 (可以拖拽)
      <span id="box_close">【关闭】</span>
    </div>
    <div class="bd"></div>
  </div>
  <script>
    var d_box =document.getElementById("d_box");
    var body =document.getElementById("bo");
    var drop =document.getElementById("drop");
    var box_close =document.getElementById("box_close");
    var nav =document.getElementsByClassName("nav");
    var bd =document.getElementsByClassName("bd");
    drop.onmousedown = function a(e) {
      e = e || window.event;
      var lx = e.clientX-d_box.offsetLeft;
      var ly = e.clientY-d_box.offsetTop;
      body.onmousemove = function b(e) {
        d_box.style.left = e.clientX-lx+"px"
        d_box.style.top = e.clientY-ly+"px"
      }
    }
    body.onmouseup = function (e) {
      body.onmousemove =null

      }
  </script>
</body>

</html>